The present invention relates to instrumentation for a rotary wing aircraft, and more particularly to an integrated hover display to provide a pilot with augmented symbology cueing which facilitates approach and landing when visually-restrictive conditions are encountered.
Rotary wing aircraft are routinely required to approach and land at remote sites without navigation guidance or acceptable visual conditions. Often the topography, ground hazards, obstacles and weather in the area are unknown or changing. Upon arrival at the remote site, the pilot must typically make critical judgments based on incomplete or inaccurate data in order to determine the proper procedure to approach and land. If the terrain condition is such that dust, snow, sand, or the like will be stirred by rotor downwash, the rotary wing aircraft may become engulfed in a cloud of visually-restrictive material. This is commonly referred to as a degraded visual environment (DVE) or a “brownout/whiteout.”
Research including literature reviews, pilot interviews, and military incident reports indicate that incidents due to DVE conditions often occur because the pilot becomes spatially disoriented due to loss of visual references. During approach to hover and landing, the pilot manipulates the aircraft controls to conduct a constant deceleration of longitudinal velocity while coordinating a rate of descent to the ground in such a way as to arrive at the ground with little or no forward velocity and a low rate of descent. In addition to controlling a rate of descent, the pilot must also compensate for forward, aft, lateral, and heading drift.
Pilots rely on extensive training to compensate for landings in DVE conditions. Pilot workload and cockpit procedures such as cross checks greatly increase during DVE conditions as the pilot must scan multiple flight display instruments to compensate for a lack of visual landing references. Such an increase in workload further complicates tactical situations.
In addition to training pilots to effectively deal with DVE conditions, there exist partial solutions which include conventional hover displays. Conventional hover displays include a rate of descent indicator which utilizes data from pitot static sensors. Pitot static sensors provide information relative to air mass and may be inaccurate at low speed due to the influence of rotor downwash. Because of this, pilots currently estimate rate of closure to the ground through visual references, augmented by relatively crude analog indicators of height above ground as sensed by a radar altimeter. Furthermore, as the terrain itself may be uneven and cloaked due to the DVE condition, the pilots burden of assuring that the landing gear settles without undue lateral rolling of the aircraft at touchdown is further complicated.
Fore, aft, lateral, and heading drift are also components that may increase spatial disorientation in DVE situations. Conventional hover displays fail to provide cuing symbology that effectively displays such drift components.
Although rotary wing aircraft are effectively operated in DVE conditions, conventional displays have, however, heretofore not provided an integrated hover display which significantly minimizes the potential for spatial disorientation in a DVE condition.
Accordingly, it is desirable to provide an integrated hover display with augmented symbology cueing to facilitate approach, hover, and landing in DVE conditions.